138 ARISTOTLE
and that what is cooled, becoming water, come down; when this happens, growing inci-
dentally happens to the grain.) Likewise, if the grain is ruined on the threshing-floor,
not for the sake of this did it rain, to spoil it, but this was incidental. So what prevents
the parts in something that is by nature from being the same way, say the teeth growing
with the front ones sharp out of necessity, suitable for tearing, but the molars flat and
useful for grinding the food, although not happening for the sake of this, but just falling
together? Likewise with the other parts, to however many being for the sake of some-
thing seems to belong, wherever everything happened to come together just as if it had
been for the sake of something, these were preserved, having been put together advan-
tageously by chance. Anything that is not like that has perished and still perishes, just as
Empedocles says of man-headed offspring of cattle.
The account, then, by means of which one might come to an impasse, is this one
or any other that might be of this kind; but it is impossible for things to be this way. For
these things and all things that are by nature come about as they do either always or for
the most part, but none of the things from fortune or chance do. For it does not seem to
be from fortune or by coincidence that it rains often in winter, but it does if this happens
in the dog days, nor scorching heat in the dog days, but in winter. If, then, it seems that
something is either by coincidence or for the sake of something, and if things by nature
cannot be by either coincidence or chance, they would be for the sake of something. But
surely such things are all by nature, as even those making these arguments would say.
Therefore, there is being-for-the-sake-of-something among things that happen and are
by nature.
Further, among all things that are for some end, it is for the sake of this that what
precedes it in succession is done. Accordingly, in the way that one performs an action,
so also are things by nature, and as things are by nature, so does one perform each
action unless something interferes. But one acts for the sake of something, and therefore
what is by nature is for the sake of something. For example, if a house were something
that came into being by nature, it would come about in just the way that it now does by
art, and if the things by nature were to come about not only by nature but also by art,
they too would come about in exactly the same way as they do by nature. Therefore
each is for the sake of another. And in general, art in some cases completes what nature
is unable to finish off, but in others imitates nature. If then, what comes from art is for
the sake of something, it is clear that what comes from nature is too, for the series of
things from art and from nature are alike, each to each, in the way that the later things
are related to the earlier.
This is clear most of all in the other animals, which do nothing by art, inquiry, or
deliberation; for which reason some people are completely at a loss whether it is by
intelligence or in some other way that spiders, ants, and such things work. But if we
move forward little by little in this way, it becomes apparent that even in plants what is
brought together comes about in relation to the end, as the leaves for the sake of protec-
tion for the fruit. So if both by nature and for the sake of something the swallow makes
a nest and the spider a web, and the plants make their leaves for the sake of their fruit,
and their roots not upward but downward for the sake of nourishment, it is clear that
there is such a cause in things that come into being and are by nature. And since nature
is twofold, both material and form, and the latter is an end but the former is for the sake
of an end, the form would be the cause for the sake of which.
Now missing the mark happens even among things done according to art (for the
grammarian on occasion writes, or the doctor gives out a drug, incorrectly), so it is clear
that this is possible also among things done by nature. But if there are some things20253035199 a51015202530199 b